JP3185048B2 - Flat flexible cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat flexible cable having ground means for shielding.

[0002]

2. Description of the Related Art Conventionally, one side (surface) of a flexible insulating substrate.
There is known a flat flexible cable in which a plurality of signal lines are provided along a longitudinal direction, and ground means for shielding is provided on the other side surface (back surface) of the flexible insulating substrate. Initially, the grounding means was formed of a metal plate that covered the entire back surface of the flexible insulating substrate. It has been proposed.

[0003]

In the flat flexible cable in which the ground means is formed of a metal net as described above,
Although the flexibility of the flat flexible cable was secured, the plurality of signal lines provided on the surface of the flexible insulating substrate and the ground means intersect each other with the flexible insulating substrate interposed therebetween. As a result of different positions for each signal line, there is a problem that the high-frequency impedance of each signal line becomes non-uniform.

The present invention has been made in view of the above problems, and is a flat flexible cable in which a signal line is provided on one side of a flexible insulating substrate and ground means is provided on the other side. It is an object of the present invention to provide a flat flexible cable having flexibility and uniform high-frequency impedance of each signal line.

[0005]

According to the present invention having the above object, the ground means provided on the other side surface (back surface) of the flexible insulating substrate is made of a conductive material having random meshes. Things.

That is, the present invention provides a flat flexible cable in which a plurality of signal lines are provided on one side of a flexible insulating substrate along a longitudinal direction, and ground means is provided on the other side of the flexible insulating substrate. 5. The flat flexible cable according to claim 1, wherein the ground means is made of a net-shaped conductive material, and each mesh of the net-shaped conductive material has an uneven shape.

A flat flexible cable in which a plurality of signal lines are provided along one side of a flexible insulating substrate along a longitudinal direction and ground means is provided on the other side of the flexible insulating substrate. The flat flexible cable is characterized in that the grounding means is made of a net-shaped conductive material, and the size of each mesh of the net-shaped conductive material is not uniform.

In a flat flexible cable, a plurality of signal lines are provided on one side of a flexible insulating substrate along a longitudinal direction, and ground means is provided on the other side of the flexible insulating substrate. The flat flexible cable is characterized in that the grounding means is made of a net-shaped conductive material, and intersections of the net-shaped conductive materials are arranged at irregular positions.

Further, in a flat flexible cable in which a plurality of signal lines are provided on one side surface of a flexible insulating substrate along a longitudinal direction and ground means is provided on the other side surface of the flexible insulating substrate, The ground means is made of a net-shaped conductive material, and intersections of the net-shaped conductive materials are arranged at irregular positions, and the shapes and sizes of the meshes are formed unevenly. It is a flat flexible cable characterized by the following characteristics.

[0010]

According to the flat flexible cable of the present invention, the mesh of the conductive material constituting the ground means is random and loses regularity. Therefore, the position where the signal line intersects such a conductive material with the flexible insulating substrate interposed therebetween is also a random position for each signal line. When each such signal line is viewed in the longitudinal direction of the flat flexible cable, the distribution capacitance of each signal line is averaged, and as a result, the high-frequency impedance of each signal line can be made uniform. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 and FIG. 2 show a flat flexible cable 1 according to an embodiment, in which a plurality of signal lines 3 are provided along the longitudinal direction on the surface (back side of the figure) of a strip-shaped flexible insulating substrate 2. In addition, a ground means made of a net-shaped conductive material 4 is provided on the back surface (front side in the figure) of the flexible insulating substrate 2 so as to cover substantially the entire back surface. Each signal line 3 extends along the longitudinal direction of the flexible insulating substrate 2 and is parallel to each other.
On the other hand, in the conductive material 4 constituting the ground means, the positions of the intersections 6 between the line portions 5 are arranged at irregular positions, and the size and shape of each mesh 7 are not uniform (FIG. 2).

As shown in FIGS. 3 and 4, the shape and size of the mesh 7 of the mesh-shaped conductive material 4 are as follows. A mesh pattern having a uniform shape and size is set. Next, the position of the intersection 6a between the line portions 5a is determined based on a random number table.
For example, it is obtained by displacing vertically (Y direction) and left and right (X direction). As a result, a random mesh 7 having a non-uniform shape and size as described above is obtained. is there.

In the flat flexible cable 1 of the above embodiment, the position where the signal line 3 intersects the line portion 5 of the conductive material 4 with the flexible insulating substrate 2 interposed therebetween has a uniform shape as shown in FIG. The mesh 7a does not repeatedly intersect at a fixed position, but appears at an irregular position. That is, the distribution capacitance between the signal line 3 and the conductive material 4 is such that a random distribution capacitance is connected in parallel with each signal line 3. As a result, the distribution capacitance of any of the signal lines 3 is averaged by combining random distribution capacitances, and the high-frequency impedance of each signal line 3 becomes substantially uniform. This enables high-speed transmission of the converted signal.

[0015]

As described above, according to the flat flexible cable of the present invention, the high-frequency impedance of each of the plurality of signal lines provided on one side of the flexible insulating substrate can be made substantially uniform. In addition, there is an excellent effect that a flat flexible cable suitable for high-speed transmission can be provided while having flexibility.

[Brief description of the drawings]

FIG. 1 is a rear view of a flat flexible cable according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG. 1;

FIG. 3 is a diagram illustrating a net pattern that is initially set when a net pattern of a net-shaped conductive material of a flat flexible cable according to an embodiment of the present invention is derived.

FIG. 4 is an enlarged view of a portion B in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat flexible cable 2 Flexible insulating substrate 3 Signal line 4 Conductive material 5 Wire part 6 Intersection of wire part 7 Mesh

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-104200 (JP, A) JP-A-2-73699 (JP, A) Jiko 1-32392 (JP, Y2) (58) Survey Field (Int.Cl. ⁷ , DB name) H01B 7/08 H01B 11/06 H05K 9/00

Claims (4)

(57) [Claims] A plurality of signal lines (3) are provided on one side surface of a flexible insulating substrate (2) along a longitudinal direction thereof.
In the flat flexible cable 1 provided with a grounding means on the other side, the grounding means is made of a net-shaped conductive material 4, and the shape of each mesh 7 of the net-shaped conductive material 4 is uneven. Flat flexible cable characterized by having a flexible shape. A plurality of signal lines provided on one side surface of the flexible insulating substrate along a longitudinal direction;
In the flat flexible cable 1 provided with a ground means on the other side, the ground means is made of a net-shaped conductive material 4, and the size of each mesh 7 of the net-shaped conductive material 4 is not sufficient. Flat flexible cable characterized by being uniform. 3. A plurality of signal lines 3 are provided on one side surface of a flexible insulating substrate 2 along a longitudinal direction.
In the flat flexible cable 1 provided with a grounding means on the other side, the grounding means is made of a net-shaped conductive material 4, and intersections 6 of the net-shaped conductive material 4 are located at irregular positions. Flat flexible cable characterized by being arranged. 4. A plurality of signal lines 3 are provided on one side surface of a flexible insulating substrate 2 along a longitudinal direction.
In the flat flexible cable 1 provided with a grounding means on the other side, the grounding means is made of a net-shaped conductive material 4, and intersections 6 of the net-shaped conductive material 4 are located at irregular positions. A flat flexible cable, wherein the flat flexible cables are arranged so that the shape and size of each mesh 7 are uneven.